Aircraft, especially combat aircraft, frequently have detachable external loads, for instance weapons or additional fuel tanks. These external loads are generally attached at two points on the aircraft, for instance under the fuselage or bearing surface. Hooks and eyes are used to attach the external loads, it being possible to open the hooks and/or the eyes for launching the external loads. In addition, ejection devices are provided that thrust the external load away from the aircraft when an external load is launched.
When external loads are launched from an aircraft, it must be ensured that no part of the aircraft is struck and damaged by the external load that is launched. To this end the ejection devices are normally adjusted such that the external load is thrust away from the aircraft and simultaneously caused to rotate so that the nose of the external load moves downward (“pitches down”). This pitch-down movement by the nose causes the oncoming air to act on the top of the external load, pressing it further downward, that is, away from the aircraft. As a rule this ensures that there is no risk of the external load colliding with the aircraft.
However, there are situations, especially with large and light-weight external loads, such as for instance empty tanks, in which this known measure does not necessarily lead to the desired success. Due to their relatively low weight, large and light-weight external loads are subject to considerable lifting forces that, despite the induced downward pitch of the nose and the flow of air acting on the top of the external load, may cause the tail of the external load to move upward towards the aircraft due to the lifting forces. This may cause critical situations, especially if the external load is suspended beneath the aircraft fuselage. In aircraft that are provided with a low-set elevator there is the danger that the upward lifting tail of the external load will strike the elevator even when external loads are suspended beneath bearing surfaces.
Today launching external loads, especially empty tanks, therefore requires that certain flight maneuvers be executed that reduce the risk of the launched load colliding with parts of the aircraft.